Heat transfer tube



June 10, 1941. M. PASCALE HEAT TRANSFER TUBE Filed Dec. 26, 1959 Patented June 10, 1941 UNITED STATES PATENT OFFICE maar rnaNsrEa TUBE Miguel mais, oakland. cam. Application December 26, 1939, Serial No. 311,050 1 claim. (ci. 257-262) This invention, a heat transfer tube, is designed for use under conditions in which heat is to be transferred from one fluid to another, such as in nre-tube or water-tube boilers, water heaters, refrigeration, and radiators o1' heating systems.

The main object of the invention is to provide a tube which will effect an absolute maximum in heat transfer as related to the volume and capacity of the tube.

Another object of the invention is to provide aA tube with integral webs or fins to increase the superiicialheat transfer area over that oi the plain tube.

A further object of the invention is to provide a tube for transfer of heat with both, inner and outer fins or Webs and so proportioned as to provide equalization of heat transfer between the inside and the outside of the tube.

A still further object of the invention is to form the additional heat transfer elements, such as the iins or webs, in comparatively shor-t sections to prevent introduction of stresses through uneven heating of inner elements relative to the exterior elements.

Other objects and advantages of the invention will become apparent as the following description is read on the drawing forming a part of this specication, and in which similar reference characters are used to designate similar parts throughout the several views, of which:

Fig. 1 is a longitudinal section through a boiler tube with the invention applied thereto.

, interior temperatures.

, Fig; 2 is a cross-sectional view showing a modification as to the number of fins as related to Fig. l. y

Fig. 3 is a modlcation of Fig. 2, showing pins substituted for the plate fins of the other types.

Fig. 4 is another modification in which the fins are formed spirally within and exteriorly of the tube.

Fig. 5 is a fragmentary longitudinal view of Fig. 4 with a portion shown in section to illustrate the interior construction.

F18. 6 is a modification showing the invention applied to a noncircular type of tubing.

Fig. 'l is a fragmentary longitudinal view of Fig. 6, and is shown partly in section.

The invention consists in forming heat transfer tubing such as ilre tubes, water tubes. steam radiators, refrigerating coils, and water heating coils, with integral heat-transfer elements, for the purpose of increasing the efllciency of the tubes to establish heat transfer at an absolute maximum without increasing the normal area of the tube or the space normally required for installation.

The Itube i0 is provided with heat transfer elements il and I2 respectively externally and internally, and these elements are preferably balanced to provide equal supercial areas solas to maintain directly relative heat transfer characteristics irrespective of variations in exterior and These elements are formed as an integral part of the tube, by either direct rolling or casting processes, or through Welding processes, so that. the ilns, webs or pins and the tube will be an inseparable and directly conductable unit.

These webs or fins in all cases are divided into short sections as shown so as to be ineffective in setting up stresses through contraction or expansion created by heat and the ends I3 and I4 of the tubes for boilers or similar uses are left free of heat transfer elements to permit installation in the flue sheets 0r boiler heads i5 and I6.

Fig. 2 is identical to Fig. 1I with the exception that eight sets of equi-angularly spaced radial heat transfer fins are included instead of two as shown in Fig. l. principally by the diameter of the tube.

Fig. 3 can be made with ns in the form of pins in any desired shape, and these pins are shown as cylindrical externally and conical internally, although Wedge or any other shape may be employed. This figure illustrates a conventional tube with a multiplicity of holes punched or drilled and pins inserted and welded in place as indicated at I9, the exterior portion Il of the pins being made to t the holes. Instead oi conical,` the interior portions I8 of these pins may also be cylindrical in form.

Figs. 4 and 5 show the invention appliedA as a series of spiral elements 2| formed exteriorly, and 22 formed interiorly of the tube 20. These spiral elements are formed similarly to the other elements, either integral with the tube as by rolling or casting, or by Welding such as by -a'continuous butt-Weld process. The spirals, similar to the straight type of fins, are divided into short sections as shown at 23 so as to eliminate the possibility of creation of, torsional stresses. Rings i can be substituted for spirals.

Figs. 6 and 7 show a structure similar to Fig. 1 with the exception that in these ilgures the invention is applied to non-circular tubing 24 and includes tie ilns 25 interiorly which act as a tie between the bulgable walls, but which tie ilns, due to the formation of the slots 26 permits com.

The number of iins is governed i munlcation throughout the cross-sectional area of the'tube.

It will be understood that variations in construction and arrangement of parts, which variations are consistent with the appended claim may be resorted to without detracting trom the spirit or scope oi the invention or sacriiicing any of the advantages thereof.

I claim:

A boiler tube substantially elliptical in crosssection and having internal webs parallel to the minor ams o! the 4tube and spaced on opposite sides thereof for heat transfer and for tying the and contraction.

MIGUEL PASCALE.

opposite sides of the Webs; 

